Kweku-Muata Osei-Bryson, Gunjan Mansingh, Lila Rao
Springer, 2014
Buku Teks
Geneva United Nations 1975,
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Honold, Linda
Davies-Black, 2000
Buku Teks
Carrin, Guy
Macmillan, 1992
Buku Teks
Page, Sheila
Overseas Development Institute, 2000
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